The invention relates to a dosing device, comprising an injection valve and a receiving device which are combined to form a structural unit by way of cohesive connections.
In known dosing devices for liquid reducing agents, such as are known for example from DE 10 2008 041 486, a dosing module is used which comprises a dosing unit, for example a dosing valve, for the injection of a reducing agent into the exhaust-gas region and which is held by a holding device or an adapter by means of which a connection to the exhaust tract is realized. To be able to introduce the reducing agent into the exhaust gas in an optimum manner, the dosing module must be positioned as close as possible to the hot exhaust tract, wherein maximum temperatures of 700° C. are reached in the exhaust tract of internal combustion engines. Owing to this inevitably high introduction of heat into the dosing module, there is the risk of overheating of the materials, for example of those used for insulators and seals, which permanently impairs the functionality of the dosing unit. For reasons relating to component strength and material protection against overheating, cooling devices are known which are intended to ensure a limit temperature of the dosing module, which is not to be exceeded, of approximately 150° C.
DE 10 2009 047 375 A1 discloses a dosing module for the dosing of a reducing agent into the exhaust tract of an internal combustion engine, which dosing module is assigned a cooling device. Aside from passive cooling by way of cooling fins on the dosing module, use is made of a cooling body filled with a fluid. For example, a cooling housing comprises a metal sleeve and plastics parts, wherein said cooling housing may be of multi-part form and is sealed off by way of O-rings and is mounted on a receiving sleeve of the dosing module.
WO 2012/049175 discloses a holder for an injector, for example for the introduction of a liquid substance into an exhaust gas of an internal combustion engine, wherein the injector is received entirely in a main body and a cap. The main body is formed from metal sheets which are connected to one another, for example by way of a brazed or welded connection, which metal sheets together form a ring-shaped chamber, wherein the injector accommodated therein is radially enclosed by said ring-shaped chamber and thus constitutes a heat barrier. The ring-shaped chamber, which is partially delimited by the housing of the injector, is charged with a cooling medium. The main body and injector housing are adhesively bonded, or connected in positively locking fashion by way of flanging, to one another in the abutment regions. The leak-tightness of the system is achieved by way of at least one seal which supplements the adhesive connections. The use of elastomers for sealing, mounting and/or insulation limits the maximum admissible temperature of the dosing module. Furthermore, the protection of the dosing valve installed in a dosing module with respect to the surroundings, for example spray water, or, on the exhaust-gas side, with respect to the reducing agent, is ensured only to a limited extent.